The probable exit of Israeli Prime Minister Ariel Sharon from the political stage of the Middle East would leave a vacuum so big that in the near term only confusion could fill it, regional experts said Wednesday.

The apparent end of the Sharon era, which was barely more than idle gossip when the aging soldier seemed to recover handily from an earlier stroke, struck Israelis full force late Wednesday when news broke of the prime minister's second, far more serious hospitalization.

While an Israeli government press release noted only that Sharon had felt unwell and ceded authority to Deputy Prime Minister Ehud Olmert while being treated under anesthetic, Israeli media was far less tentative.

"One can cautiously say that it appears that the era in which Sharon stood at Israel's helm came to a tragic end on Wednesday," proclaimed the daily Haaretz on its English-language Web site.

The timing could hardly be more dramatic.

Palestinian parliamentary elections, the first in 10 years, are supposed to be held later this month, pitting Israel's sometime partner in negotiations, Fatah, led by President Mahmoud Abbas, against Hamas, the Islamic movement that still calls for the destruction of Israel. Abbas has threatened to postpone the poll if the Israeli government goes ahead with its threat to prevent Palestinians from voting in East Jerusalem, which is under Israeli control.

At the same time, Israel is gearing up for its own election, which opinion polls suggested Sharon's newly minted party, Kadima, would win handily. Now political observers wonder if the party -- widely perceived as essentially a one-man show -- could survive without him.

All of this is happening just months after Sharon all but single-handedly rewrote the terms of debate in the Middle East, forcing his longtime supporters in the Jewish settlement movement to cede territory in Gaza and the West Bank to the Palestinians even as he consolidated his hold on large tracts of contested land near Jerusalem.

"This is a man who is by no means a dove, but was willing to take very dramatic steps that flew in the face of conventional wisdom ... to do what he thought was necessary to advance Israeli security," said Tamara Wittis, an expert on the Middle East at the Saban Center at the Brookings Institution.

"But because he was one of the founding generation, Israelis trusted him. With the loss of a figure like that, there isn't really anyone left who could carry that mantle, and the question is, whom would Israelis trust to carry that mantle and make bold moves for peace. And it's possible that there isn't anyone."

Analysts agree that Sharon was able to tap into a new Israeli political center -- one he helped forge -- which embraced both disengagement from some Palestinian territories while building a barrier that Palestinians believe effectively annexes much of their territory. "The (Kadima) party without him will continue to reflect this very important change in the Israeli political scene," Feldman said. However, he added, much of Sharon's power derived from his status as "a kind of a father figure, to some extent similar to the manner in which (Yitzhak) Rabin acquired the character of a national father figure" before he was assassinated by a right-wing Jewish extremist in 1995.

Former Prime Minister Shimon Peres, at 82, has some of that heft, and there has been some speculation about his future in the wake of Sharon's incapacitation. But as Labor's leader, Peres lost more national campaigns than he won, and while he left Labor to join Kadima, he will not lead the new party in Sharon's absence.

The man who does, former Jerusalem Mayor Olmert, is in some ways a lightly drawn carbon copy of Sharon, some experts said -- well known, if not in the same league as Sharon, and with a history, like Sharon's, of moving from hawkish absolutism on security to outright support for disengagement.

But that familiarity might not be enough to guarantee Olmert the support of his fellow ministers in Kadima -- a party that includes dissimilar politicians from both Labor and Likud -- much less the broad Israeli middle.

But his rivals are new and weak, too, experts note: Labor leader Amir Peretz, better known for his social economic policies than his strong security stance, and Benjamin Netanyahu, perceived by many Israelis as too hawkish and by some as untrustworthy.

With all of that uncertainty, the future of Israeli politics -- assuming Sharon does not return to power -- may be decided in part by another party: the Palestinians, whose reaction to the change in leadership -- violent or quiet -- could greatly impact Israeli opinion.

"The Palestinians have played a major role in all the Israeli elections since 1993," said Gershon Shafir, a professor of sociology at UC San Diego. "You could almost say they are kingmakers at certain critical political junctures."

In that light, Sharon's departure could have even greater repercussions on the Middle East than did the death of his former nemesis, Yasser Arafat.

"Arafat died at a moment when he could not have contributed that much more, or was not willing to contribute that much more to the peace process," Shafir said. "Sharon seems to be on the way out ... at a time when he was in the process of changing his own spots."

Sharon is a deeply divisive figure among Palestinians. Many blame him for massacres of Palestinian refugees in camps in Lebanon in 1982 and for sparking the second Palestinian uprising with a controversial visit to the Temple Mount in 2000.

But initial Arab reaction to Sharon's condition has been somewhat muted. The Lebanese camps where the massacres took place were reported to be quiet, and a Palestinian commentator on the Saudi-owned Al-Arabiya network offered Sharon unexpected praise as "the first Israeli leader who stopped claiming Israel had a right to all of the Palestinian's land," a reference to Israel's recent withdrawal from the Gaza Strip.

"A live Sharon is better for the Palestinians now, despite all the crimes he has committed against us," Ghazi al-Saadi was quoted as saying.

With so much uncertainty, many Palestinians and their leaders are likely to see the wisest course to be waiting and seeing what happens with Israel's political situation, the experts said. What happens in the longer term is an open question.

"Short term I don't think it will have a dramatic effect," said Nathan Brown, a senior associate at the Carnegie Endowment for International Peace. "But in the medium term and the long term it shakes up the equilibrium and basically plunges us into the unknown."